Process of producing matte finish



Patented Dec. 15, 1925.

UNITED STATES PATENT OFFICE.

WILLIS R. WHITNEY, OF NISKAY'UNA, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY,

A CORPORATION OF NEW YORK.

PROCESS OF PRODUCING MATTE FINISH.

No Drawing.

To all whom 2'25 may concern:

Be it known that I, lVILLIs R. WHITNEY,

a citizen of the United States, residing at Niskayuna, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in the Process of Producing Matte Finish, of which the following is a specification.

The present invention relates to the manul" facture of articles containing a substantial proportion of a filler or binder consisting of a heavy hydrocarbon compound, such as asphalt, bitumen or tar.

It is the object of my invention to produce upon the surface of articles of this nature a matte or dull-surface instead of the normally shiny surface.

My invention is particularly applicable to the production of a matte finish on asbestos board made by the use of a mineral binder, for example, magnesia, or Portland cement, and containing impregnated in its pores an asphaltic material derived from still wax or petroleum tailings by heating.

It has been attempted to remove the unattractive, shiny, superficial layer consisting largely of asphaltic or tarry material by mechanical means, such as sand blasting but this treatment results in a whitish streaky appearance due to the slight disintegration of the asbestos and the removal of the asphaltic coat from the asbestos fibres. The

ordinary pickling acids also give an unattractive appearance, or else have no effect. I have discovered that the desired matte finish may be obtained by treatment with a reagent, such as a concentrated acid, which will attach the asphaltic material itself leaving a substance of a dull, dark appearance and being perhaps of carbonaceous nature. In carrying out my invention, the articles containing the material of asphaltic nature, as, for example, mineral compositions which \have been impregnated with asphaltic ma- \terial, are treated with strong sulphuric Application filed May 28, 1924. Serial No. 716,516.

acid. When the acid has been in contact with the shiny surface for a few minutes the surface becomes matte, resembling slate. The acid then is removed by washing and the material is dried.

It is more suitable for the manufacture of switchboard panels, and the like, in which a neat, artistic appearance is desired than the untreated material.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The process of producing a matte finish upon compositions containing an asphaltic binder and having in an untreated state a shiny surface composition with a mineral acid which is capable of etchingsaid surface.

2. The process of producing a matte finish upon an article having a surface layer containing a substantial proportion of normally shiny organic substance which consists in chemically decomposing said organic substance at the surface.

3. The process of producing a matte finish upon an article having a surface layer containing a substantial proportion of asphaltic material which consists in treating the surface of said article with concentrated sulphuric acid, and thereupon washing to remove said acid.

a. An article of manufacture comprising a composition of a mineral material and still Wax pitch having an external layer containing a substantial proportion of pitch residue modified with sulphuric acid having a dull, matte surface.

5. An article of manufacture comprising asbestos board containing asphalting material in suflicient quantity to have normally a shiny appearance, and having a matte surface produced by etching of the superficial layer of said board.

In witness whereof, I have hereunto set my hand this 27th day of May, 1924.

\VILLIS R. WHITNEY.

which consists in treating said- 

